1. Technical Field
The present invention relates to an optical scanner, an actuator, an image display device, and a head-mounted display.
2. Related Art
For example, optical scanners that are used in projectors, head-mounted displays, and the like to two-dimensionally scan light have been known (for example, see JP-A-2003-207737).
For example, the optical scanner described in JP-A-2003-207737 has a frame-like external frame (a fixed portion), an internal frame (a frame body portion) provided inside the external frame, a pair of second elastic beams (a second shaft portion) adapted to rotatably support the internal frame with respect to the external frame, a mirror portion (a movable portion) provided inside the internal frame, and a pair of first elastic beams (a first shaft portion) adapted to rotatably support the mirror portion with respect to the internal frame.
In the optical scanner, the internal frame is rotated relative to the external frame during torsional deformation of the second elastic beams, and the mirror portion is rotated relative to the internal frame during torsional deformation of the first elastic beams to two-dimensionally scan light reflected on the mirror portion.
In addition, in the optical scanner described in JP-A-2003-207737, a piezoresistor is disposed on the first elastic beam between the mirror portion and the internal frame. Accordingly, it is possible to detect the rotation of the mirror portion that is carried out due to the torsional deformation of the first elastic beams, based on a variation in resistance value of the piezoresistor.
In the optical scanner described in JP-A-2003-207737, the piezoresistor is provided on the first elastic beam between the mirror portion and the internal frame, and thus it is necessary to arrange wiring for supplying electric power to the piezoresistor and wiring for extracting a detection signal of the piezoresistor over an entire area on the second elastic beam between the internal frame and the external frame.
When the wirings are formed over the entire area on the second elastic beam as described above, the wirings pass on a portion where the amount of the deformation by the torsion of the second elastic beam reaches a maximum, and thus repetitive stress is received due to the torsional deformation of the elastic beam, and thus there is concern that the wirings may be disconnected.